For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningWater Management Description and Operation
Plenum Water Flow Direction and Cleaning
A large percentage of water will flow off the windshield area into the plenum
chamber drain system and then down the outside on the
plenum to the underside of the vehicle. To ensure that the plenum chamber water
management system performs properly, the ...
Interior Trim and Paneling
Specifications
Front Side Door Window Switch Bezel Replacement
Preliminary Procedure
Remove the front side door trim. Refer to Front Side Door Trim Replacement.
Front Side Door Window Switch Bezel Screw (Qty: 8)
Caution: Refer to Fastener Caution in the Preface section.
Tighten
...
Rear Side Door Wiring Harness Replacement
Preliminary Procedure
Remove the rear side door inner panel trim. Refer to Rear Side Door Trim
Replacement.
Rear Side Door Wiring Harness
Warning: Unless directed otherwise, the ignition and start switch must be
in the OFF or LOCK position, and all electrical
loads must be OFF befor ...